29 



the student can obtain are (1) the possession of a compound micro- 

 scope with powers of from 40 to 400 diameters, and with an eje- 

 piece micrometer ; (2) the possession of a set of authentic specimens, 

 without which it is often difficult to determine Lichens even with the 

 aid of published descriptions. The only set of Exsiccati of our 

 Lichens was that published by Tuckerman many years ago of New 

 England Lichens, which is now out of print. (3) Books, the most 

 useful of which to the American student are the works of Tucker- 

 man, especially the Genera and the Synopsis, both of which should 

 be in the hands of every student. To these should be added, if at- 

 tainable, his Observations in the Proceedings of the American Acad- 

 emy, his Lichens of California, and his occasional descriptions of 

 new Lichens in the Torrey Bulletin. Of foreign books, the most 

 valuable to the beginner will be Nylander's Synopsis. The Cuban 

 lichens collected by Charles Wright have been described by Tucker- 

 man, Nylander, and Miiller ; but the Graphidese yet remain to be 

 described. Many Lichens of this Flora are likely to be found in 

 Florida. If the student is desirous of extending his knowledge to 

 European authors, he can obtain some of the Exsiccati of that coun- 

 try, of which the most beautiful is Norrlin and Nylander's collection 

 of Finnish Lichens, elegantly put up, and containing about 250 

 numbers. This Flora is much like that of the northern part of this 

 country. Of books we will mention a few of the more important. 



For the earlier periods Acharius, Lichenographia Universalis and 

 Synopsis ; Fries, Lichenographia Europaea Eeformata ; Eschweiler, 

 Systema Lichenum ; F^e, Essai and Supplement. Of more recent 

 authors, all the writings of Nylander are valuable, especially the 

 Lichenographia Scandinavica and Supp., Expositio Pyrenocarpeo- 

 num. Lichens of New Granada, and Eecognitio Eamalinorum. For 

 many years he has contributed descriptions of new European Li- 

 chens to the Eegensburg Flora, and these have recently been col- 

 lected into a volume published in Paris. Miiller has described many 

 European and exotic Lichens in the same journal. Of Theodore M. 

 Fries may be mentioned Lichenographia Scandinavica, of which only 

 one volume is published, and Genera Heterolichenum Europse. 

 Wainio's Adjutamenta, in connection with the works of Nylander 

 and Th. Fries, furnishes valuable but often discordant observations 

 on the Acharian Lichens. We have already given the titles of the 

 works of Scbwendener and Minks. Many other contributions to 



